Electrode for stabilizing the cathode spot of mercury arc devices



A llg. 28, 1934. A AMlLLAC 1,971,805

4ELEC'IRODE FOR STABILIZING THE GATHODE SPOT 0F MERCURY ARC DEVICESFiled June-7. 1952 Albert Arnllac, 'IOL MOL/6M JH is Attom-weg.

Patented Aug. Z8, 1934 `FFIC ELECTRODE FOR STABILIZING THE CATH- ODESPOT OF MERCURY ARC DEVICES York Application June 7, 1932, Serial No.615,897

In France July 24, 1931 6 Claims. (Cl.` Z50-27.5)

`My invention relates t o the cathodev structure of mercury arc devices,particularly to refractory electrodes mounted in the mercury poo-1 ofsuch devices, and has for its object the provision of an improvedelectrode arrangement of this character for stabilizing the cathode spotposition.

It has already been proposed to maintain in a fixed position the cathodespot of mercury arc rectiers and similar' electrical apparatus by meansof a refractory electrode of suitable form,V

composed of tungsten, molybdenum, tantalum, etc., or of variouscompounds such as borides, silicides'orI metallic carbides. It is knownthat such stabilization of the cathode spot position insures, inapparatus so characterized, various advantages among which particularlyis the possibility 'of i opeartion at a low load and the possibility ofreducing, other conditions being equal, the quantity of vapor, ofVmercury or other material, whichV is required in the apparatus. Mypresent invention is directed to an improvement in the means forstabilizing the position of the cathode spot of the apparatus underconsideration. This improvement is essentially character,-

2 ized by the fact that cuts,'slits or other capillary spaces areprovided in the cathode spot stabilizing electrode. 'I'he inventionextends also, in combination with the above first-mentioned means, tocomplementary means consisting in an increase, with respect to the massused up to the present, of the mass of the 'cathode-spot stabiliz-` ingelectrode and of its thermal conductivity, and

also in an increase with respect to lengthused heretofore, of the.length of the line of stabiliza- 5 tion with respectto the dimensionsand mass of the electrode. These two complementary means may be utilizedseparately or in combination.

The above meansto which my invention is directed increase the stabilityof the ixing of the cathode spot,`the increase of the mass and of the.

thermal conductivity of the electrode avoiding eX- cessive heating ofthe electrode and the disappearanceat its surface of the iilm of cathodematerial, .the existenceof which .is necessary for maintaining thestabilizing effect on the cathode spot position. i i.

My invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawing and itsscope will be pointed out in the appended claims.

Referring to the drawing, Figs. 1 and 2 illustrate schematically theposition in the cathode container of a vapor electric device such as amercury arc rectifier, of cathode spot stabilizing 5 electrodes inaccordance with my invention; Fig.

3 is a cross-'sectional view of an electrode online 3-3 of Figs. 1 and2; Fig. 4 is a side elevation of certain of the electrode elements shownin Fig. 3; Fig. 5 is a plan view of the electrode shown in Fig. 3; Fig.6 is an enlarged View of a portion of Fig.` 5 and illustratesschematically the position of the cathode spot with relation to thestabilizing electrode; and Fig. 7 is a pian view illustrating a modifiedform of the invention.

In Figs. land 2 the numeral l() designates the cathode container of amercury arc device such as a rectier and the numeral 11 designates thepool of mercury within the container. In order to maintain the cathodespot of mercury pool 11 in a `fixed position along a predetermined linea stabilizing electrode of refractory material, designated by the lines12 and 13 in Figs. 1 and 2 respectively, is mounted in thefcontainer 10.The form of this electrode and the manner of mounting thereof in thecontainer will be explained hereinafter.

In the form of the invention illustrated in Figs. 3 to 6, the electrode12 or 13 of Figs. 1 or 2, for maintainingthe .position of the cathodespot, is constituted by a suitable number of ribbons of refractory metal14, 15, 16, 17, which are separated from one another by ribbons 18, 19,20 formed of any suitable metal which is `not attacked by mercury andthe thickness of which corresponds to the capillary space which it isdesired to establish between the portions 14, 15, 16, 17 of the spotstabilizing electrode. The ribbons 18, 19, 20 are not as high as theribbons 14 to 17 and do not emerge from the mercury 11. The assembly orunit formed by ribbons 14 to 17 and 18 to 20 is mounted by a member 21upon a salient portion or rib 22 integral with the wall of thereceptacle containing the mercury 11.

In order to eiiect the fixing in position of the cathode spot bycapillarity, which is the object of. the invention, the ribbons 14, and16 of the refractory ribbons 14 to 17 are indented as shown in Fig. 4,and a suitable number of such ribbons according to the maximum rectifiedcurrent are then pressed against the rib 22, the indented ribbons beingin staggered relation or displaced one with respect to anotherconformably to the arrangement represented in Fig. 5 in which are shownthe upwardly projecting portions of ribbons 14', 15 and 16. The innerribbon, designated in the drawing as 17, is not indented and serves toinsure a continuous line of stabilization or iixation of the cathodespot between the various groups of the teeth portions of ribbons 14, 15and 16, which constitute in eiect a corresponding ccf los

number of spot fixation elements through the eiect of capillarity. Atpoints 23 to 28, as shown in Fig. 6, at the ends of the capillary spacesformed between the adjacent tooth portions of the ribbons 14, 15, 16,and between the ribbons 16 and 17 by the narrow intermediate ribbons,appear regions in which the spot stabilizing `or positioning effect isvery pronounced. The ribbon 17, which is not indented insures, as aboveexof xation corresponds to the dotted lineA 29 shown in the enlargedview, Fig. 6, and enfolds a number of capillary iixationV elements whichis proportional to the current supplied by the cathode. The solid orunindented ribbon 17 may advantageously comprise at intervals verynarrow vertical slits such as 30 forming so many added points of cathodespot fixation through the effect of capillarity.

Fig. 7 shows a modification of the invention in which the solid orunindented interconnecting electrode element 17 is arranged in thecenter of groups of indented ribbons to the number of six, 14 to 16 and31 to 33. In this manner is obtained an improvement on the arrangementshown in Fig. 5 whereby the cathode spot may be maintained in positionwith the same effectiveness indifferently on one or the other of thegroups of surfaces comprised in the arrangement for the fixation of thecathode spot.

Other forms of fixation electrodes may be ernployed in which areprovided slits, cuts or other capillary spaces, without departing fromthe scope of the invention. For example, the electrodes may emergeobliquely from the mercury or, further, may have the form of segments ofacylinder the point of emergence of which is substantially tangent tothe surface of the mercury.

The cathode spot xation electrodes in accordance with the inventionpresent preferably a continuous line which forms on the cathode surfacespiral, zigzag or oblong patterns. Figs. 1 and 2, in which the numeralsl2 and 13 represent fixation electrodes forming continuous lines on thecathode surface show schematically two forms of such arrangements.

In the form shown in Fig. 1 the fixation electrode takes the form of aspiral formed by nearly circular elements 34 which are concentric andare interconnected by straight elements 35. The object of thisarrangement is to simplify the machining of the ribs formed in thecathode receptacle and against which the xation electrode is pressed.

Fig. 2 shows a zigzag arrangement of the xation electrode which ispressed against parallel ribs provided on the cathode receptacle.

It is to be understood that the schematic iigures of the drawingillustrate various cathode spot fixation electrodes in accordance withmy invention and are given by way of examples merely and not aslimitations thereof. The particular arrangements which have beendescribed in connection with the figures are to be considered as beingcontemplated by my invention, it being understood that all equivalentarrangements may be utilized without going beyond the scope of theinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1,. In a vapor electric device having a liquid cathode, a relativelylong and narrow auxiliary electrode horizontally vdisposed throughoutits length in said cathode and having portions projecting upwardly fromthe surface thereof a substantial distance for stabilizing the positionof vthe cathode spot on said cathode, said auxiliary electrode includinga plurality of relatively thin ribbon members spaced apart throughouttheir ylength to form capillary spaces therebetween.

2. In a vapor electric device having a liquid cathode, a relatively longand narrow auxiliary electrode horizontally disposed throughout itslength with reference to said cathode and having a portion immersedtherein for stabilizing the position of the cathode spot thereon, saidauxiliary electrode including a plurality of relatively thin ribbonmembers spaced apart throughout their length to form capillary spacestherebetween, said ribbon members including tooth portions projectingupwardly a substantially distance from the surface ci said cathode.

3. In a vapor electric device having a liquid cathode, an auxiliaryelectrode immersed in said cathode for stabilizing the position of thecathode spot thereon including a plurality of toothed ribbon membersspaced apart throughout their length to form capillary spacestherebetween, the tooth portions of said ribbons being in staggeredrelation.

4. In a vapor electric device having a liquid cathode, an auxiliaryelectrode immersed in said cathode forstabilizing the position of thecathode spot thereon including a plurality of ribbon members spacedapart throughout their length to form capillary spaces therebetween,certain of Vsaid ribbon members being toothed, said toothed portionsbeing in staggered relation, one of said ribbon members beingsubstantially continuous.

5. In a vapor electric device having a liquid cathode, an auxiliaryelectrode immersed in said cathode for stabilizing the position of thecathode spot thereon including a plurality of ribbon members spacedapart throughout the length of said auxiliary' electrode to formcapillary spaces between said ribbon members, said auxiliary electrodelbeing arranged in spiral form in said cathode.

6. In a vapor electric device having a liquid cathode, an auxiliaryelectrode immersed in said cathode for stabilizing the position of thecathode spoty thereon including a plurality of ribbon members spacedapart throughout the length of said auxiliary electrode to formcapillary spaces between said ribbon members, said auxiliary' electrodebeing arranged in zigzag form f

